1. Technical Field
The present invention relates to a sheet manufacturing apparatus.
2. Related Art
Conventionally, a so-called wet system is adopted in a sheet manufacturing apparatus to inject raw materials containing fibers into water, defibrate primarily by mechanical actions, and repulp. This kind of wet-type sheet manufacturing apparatus requires a large quantity of water, and the apparatus becomes large. Furthermore, in addition to the long time it takes for equipment maintenance of the water treatment facilities, the energy related to the drying process becomes substantial.
Therefore, a sheet manufacturing apparatus based on a dry system that uses as little water as possible in order to reduce the size and to save energy is proposed (e.g., see Japanese Laid-Open Patent Publication No. 2012-144819).
Japanese Laid-Open Patent Publication No. 2012-144819 describes defibration of pieces of paper into a fibrous form in a dry-type defibrating apparatus, classifies the fibers in a cyclone into ink particles and deinked fibers, passes the deinked fibers through a screen with small holes on the surface of a forming drum for depositing on a mesh belt, and forms into paper.
In a dry-type defibrating apparatus, the noise including the defibration sounds generated when defibrating pieces of paper is relatively large in a sheet manufacturing apparatus. Japanese Laid-Open Patent Publication No. H5-279985 discloses a sound muffler for absorbing the noise created by the rotation of a rotor inserted between the material receiving port and the housing in a crushing device that crushes ramie and hemp.
The problem of the sound muffler disclosed in Japanese Laid-Open Patent Publication No. H5-279985 is that the sudden expansion of the cross-sectional area of the pipe is used to muffle the sound, but when the flow path expands, the materials accumulate inside of the sound muffler. In addition, when a taper is provided on the downstream side to prevent the accumulation of material, the problems are the reduced performance of sound muffling, the difficulty in reducing the size because of the increased length in the transfer direction, and the inability to position horizontally.